This invention relates generally to injection molding and more particularly to an insulative and resilient spacer member to be mounted to provide an air space of a precise width between heated and cooled components of an injection molding system.
The use of spacers or pressure pads to provide insulative air spaces while withstanding very considerable injection forces are well known in the art. For instance, a solid pressure pad made of titanium to reduce heat loss is shown mounted between the heated manifold and cooled back plate in U.S. Pat. No. 4,768,945 to Schmidt et al. which issued Sep. 6, 1988. In addition to being expensive, these pressure pads have the disadvantage that they are not resilient to allow for thermal expansion and/or some slight variations in component tolerances and injection forces. A combination sealing and retaining bushing having a slightly resilient outer flanged portion for a valve gated injection molding system is described in U.S. Pat. No. 4,740,151 to Schmidt et al. which issued Apr. 26, 1988. U.S. Pat. No. 4,588,367 to Schad which issued May 13, 1986 shows a support element which is compressible to allow for thermal expansion. While these prior devices or arrangements are suitable for particular situations or applications, they have the disadvantages that they are relatively costly to make and do not have a broad application for a variety of different injection molding systems. Furthermore, with the development of smaller injection molding systems and the use of more temperature sensitive molding materials, the degree of resilience and the reduced thermal conductivity of the spacer member have become much more critical.